- ID:
- ivo://CDS.VizieR/J/PASJ/53/971
- Title:
- CO catalog of LMC molecular clouds
- Short Name:
- J/PASJ/53/971
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- From a ^12^CO (J=1-0) survey with the NANTEN telescope, we present a complete catalog of giant molecular clouds (GMCs) in the Large Magellanic Cloud. In total, 107 CO clouds have been identified, 55 of which were detected at more than 3 observed positions. For the 55 clouds, the physical properties, such as size, line-width, virial mass, and CO luminosity, are cataloged.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/PASJ/62/557
- Title:
- CO clouds in the Galactic Center from NANTEN
- Short Name:
- J/PASJ/62/557
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In order to better understand molecular clouds and their properties toward the Galactic center region, we have analyzed the NANTEN database of ^12^CO (J=1-0) and ^13^CO (J=1-0) to search for associations with candidates for young high-mass star-forming regions, such as IRAS point sources, radio continuum sources, recombination line sources, maser line sources, and other molecular line sources. We have also compared the data with TeV gamma-ray sources. The analyzed region covers -12{deg}<=l<=12{deg} and -1.5{deg}<=b<=1.5{deg} for ^12^CO, and -6{deg}<=l<=8{deg} and -1{deg}<=b<=1{deg} for ^13^CO. As a result, we identified 167 IRAS point sources, 73 recombination line sources, 58 maser sources, 107 radio continuum sources, and 77 molecular line sources associated with 169 positions with the CO emission.
- ID:
- ivo://CDS.VizieR/J/ApJ/878/44
- Title:
- ^13^CO clumps toward the Cassiopeia A supernova remnant
- Short Name:
- J/ApJ/878/44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have conducted a large-field simultaneous survey of ^12^CO, ^13^CO, and C^18^O J=1-0 emission toward the Cassiopeia A (Cas A) supernova remnant (SNR), which covers a sky area of 3.5{deg}x3.1{deg}. The Cas giant molecular cloud (GMC) mainly consists of three individual clouds with masses on the order of 10^4^-10^5^M_{sun}_. The total mass derived from the ^13^CO emission of the GMC is 2.1x10^5^M_{sun}_ and is 9.5x10^5^M_{sun}_ from the ^12^CO emission. Two regions with broadened (6-7km/s) or asymmetric ^12^CO line profiles are found in the vicinity (within a 10'x10' region) of the Cas A SNR, indicating possible interactions between the SNR and the GMC. Using the GAUSSCLUMPS algorithm, 547 ^13^CO clumps are identified in the GMC, 54% of which are supercritical (i.e., {alpha}_vir_<2). The mass spectrum of the molecular clumps follows a power-law distribution with an exponent of -2.20. The pixel-by-pixel column density of the GMC can be fitted with a log-normal probability distribution function (N-PDF). The median column density of molecular hydrogen in the GMC is 1.6x10^21^cm^-2^ and half the mass of the GMC is contained in regions with H_2_ column density lower than 3x10^21^cm^-2^, which is well below the threshold of star formation. The distribution of the YSO candidates in the region shows no agglomeration.
- ID:
- ivo://CDS.VizieR/J/MNRAS/469/521
- Title:
- CO, C & O gas content of debris discs predictions
- Short Name:
- J/MNRAS/469/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper uses observations of dusty debris discs, including a growing number of gas detections in these systems, to test our understanding of the origin and evolution of this gaseous component. It is assumed that all debris discs with icy planetesimals create second generation CO, C and O gas at some level, and the aim of this paper is to predict that level and assess its observability. We present a new semi-analytical equivalent of the numerical model of Kral et al. (2016MNRAS.461.1614K) allowing application to large numbers of systems. That model assumes CO is produced from volatile-rich solid bodies at a rate that can be predicted from the debris discs fractional luminosity. CO photodissociates rapidly into C and O that then evolve by viscous spreading. This model provides a good qualitative explanation of all current observations, with a few exceptional systems that likely have primordial gas. The radial location of the debris and stellar luminosity explain some non-detections, e.g. close-in debris (like HD 172555) is too warm to retain CO, while high stellar luminosities (like {eta} Tel) result in short CO lifetimes. We list the most promising targets for gas detections, predicting >15 CO detections and >30 CI detections with ALMA, and tens of CII and O I detections with future far-IR missions. We find that CO, CI, CII and OI gas should be modelled in non-LTE for most stars, and that CO, CI and OI lines will be optically thick for the most gas-rich systems. Finally, we find that radiation pressure, which can blow out CI around early-type stars, can be suppressed by self-shielding.
- ID:
- ivo://CDS.VizieR/J/A+A/430/549
- Title:
- C^18^O/C^17^O near rho Oph
- Short Name:
- J/A+A/430/549
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of up to ten carbon monoxide (CO and isotopomers) transitions are presented to study the interstellar C^18^O/C^17^O ratio towards 21 positions in the nearby (d~140pc) low-mass star forming cloud {rho} Oph. A map of the C^18^O J=1-0 distribution of parts of the cloud is also shown.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A131
- Title:
- 12CO/13CO ratio in 126 nearby galaxy centers
- Short Name:
- J/A+A/635/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present ground-based measurements of 126 nearby galaxy centers in ^12^CO and 92 in ^13^CO in various low-J transitions. More than 60 galaxies were measured in at least four lines. The average relative intensities of the first four J ^12^CO transitions are 1.00:0.92:0.70:0.57. In the first three J transitions, the average ^12^CO-to-^13^CO intensity ratios are 13.0, 11.6, and 12.8, with individual values in any transition ranging from 5 to 25. The sizes of central CO concentrations are well defined in maps, but poorly determined by multi-aperture photometry. On average, the J=1-0 ^12^CO fluxes increase linearly with the size of the observing beam. CO emission covers only a quarter of the HI galaxy disks. Using radiative transfer models (RADEX), we derived model gas parameters. The assumed carbon elemental abundances and carbon gas depletion onto dust are the main causes of uncertainty. The new CO data and published [CI] and [CII] data imply that CO, C, and C^+^ each represent about one-third of the gas-phase carbon in the molecular interstellar medium. The mean beam-averaged molecular hydrogen column density is N(H_2_)=(1.5+/-0.2)10^21^cm^-2^. Galaxy center CO-to- H2 conversion factors are typically ten times lower than the 'standard' Milky Way X disk value, with a mean X(CO)=(1.9+/-0.2)10^19^cm^-2^/(K.km/s) and a dispersion 1.7. The corresponding [CI]-H_2_ factor is five times higher than X(CO), with X[CI]=(9+/-2)10^19^cm^-2^/(K.km/s). No unique conversion factor can be determined for [CII]. The low molecular gas content of galaxy centers relative to their CO intensities is explained in roughly equal parts by high central gas-phase carbon abundances, elevated gas temperatures, and large gas velocity dispersions relative to the corresponding values in galaxy disks.
- ID:
- ivo://CDS.VizieR/J/ApJ/760/147
- Title:
- ^13^CO cores in the Taurus molecular cloud
- Short Name:
- J/ApJ/760/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young stars form in molecular cores, which are dense condensations within molecular clouds. We have searched for molecular cores traced by ^13^CO J=1-->0 emission in the Taurus molecular cloud and studied their properties. Our data set has a spatial dynamic range (the ratio of linear map size to the pixel size) of about 1000 and spectrally resolved velocity information, which together allow a systematic examination of the distribution and dynamic state of ^13^CO cores in a large contiguous region. We use empirical fit to the CO and CO_2_ ice to correct for depletion of gas-phase CO. The ^13^CO core mass function (^13^CO CMF) can be fitted better with a log-normal function than with a power-law function. We also extract cores and calculate the ^13^CO CMF based on the integrated intensity of ^13^CO and the CMF from Two Micron All Sky Survey. We demonstrate that core blending exists, i.e., combined structures that are incoherent in velocity but continuous in column density. The core velocity dispersion (CVD), which is the variance of the core velocity difference {delta}v, exhibits a power-law behavior as a function of the apparent separation L: CVD(km/s){prop.to}L(pc)^0.7^. This is similar to Larson's law for the velocity dispersion of the gas. The peak velocities of ^13^CO cores do not deviate from the centroid velocities of the ambient ^12^CO gas by more than half of the line width. The low velocity dispersion among cores, the close similarity between CVD and Larson's law, and the small separation between core centroid velocities and the ambient gas all suggest that molecular cores condense out of the diffuse gas without additional energy from star formation or significant impact from converging flows.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A41
- Title:
- 12CO(2-1) datacubes of 3 IR sources
- Short Name:
- J/A+A/648/A41
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Lupus star-forming complex includes some of the closest low-mass star-forming regions, and together they house objects that span evolutionary stages from pre-stellar to pre-MS. By studying 7 objects in the Lupus clouds from prestellar to protostellar stages, we aim to test if a coherence exists between commonly used evolutionary tracers. We present ALMA observations of the 1.3mm continuum and molecular line emission that probe the dense gas and dust of cores (continuum, C^18^O, N_2_D^+^) and their associated molecular outflows (^12^CO). Our selection of sources in a common environment, with identical observing strategy, allows for a consistent comparison across different evolutionary stages. We complement our study with continuum and line emission from the ALMA archive in different bands. The quality of the ALMA molecular data allows us to reveal the nature of the molecular outflows in the sample by studying their morphology and kinematics, through interferometric mosaics covering their full extent. The interferometric images in IRAS 15398-3359 appear to show that it drives a precessing episodic jet-driven outflow with at least 4 ejections separated by periods of time between 50 and 80 years, while data in IRAS 16059-3857 show similarities with a wide-angle wind model also showing signs of being episodic. The outflow of J160115-41523 could be better explain with the wide-angle wind model as well, but new observations are needed to further explore its nature. We find that the most common evolutionary tracers in the literature are useful for broad evolutionary classifications, but are not consistent with each other to provide enough granularity to disentangle different evolutionary stage of sources that belong to the same Class (0, I, II, or III). The evolutionary classification revealed by our analysis coincides with those determined by previous studies for all our sources except J160115-41523. Outflow properties used as protostellar age tracers, such as mass, momentum, energy and opening angle, may suer from differences in the nature of each outflow, and therefore detailed observations are needed to refine evolutionary classifications. We found both AzTEC-lup1-2 and AzTEC-lup3-5 to be in the pre-stellar stage, with the possibility that the latter is a more evolved source. IRAS 15398-3359, IRAS 16059-3857 and J160115-41523, which have clearly detected outflows, are Class 0 sources, although we are not able to determine which is younger and which is older. Finally Sz 102 and Merin 28 are the most evolved sources in our sample and show signs of having associated flows, not as well traced by CO as for the younger sources.
- ID:
- ivo://CDS.VizieR/J/other/PASA/17.92
- Title:
- CO emission towards Southern dark clouds
- Short Name:
- J/other/PASA/17.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the 22-m 'Mopra' antenna (near Coonabarabran, NSW) of the Australia Telescope National Facility (ATNF), we have observed emission from the 115-GHz J=1-0 transition of CO towards the centre of each of the 1101 clouds listed in the Hartley et al. Catalogue of Southern Dark Clouds (SDC, Cat. <VII/191>). The velocity range covered was -96 to +70km/s, with a velocity resolution of 0.120km/s. CO was detected at 1049 of the positions, with 367 spectra showing emission at more than one radial velocity. Here we present the most comprehensive general survey of the SDC catalogue, with the intensity, velocity and half-width of the CO detection and a code describing the profile shape. The presence of blue- or red-shifted wings in many observations can provide a starting point in searches for star-forming regions.
- ID:
- ivo://CDS.VizieR/J/A+A/412/657
- Title:
- CO in cooling flow of clusters of galaxies
- Short Name:
- J/A+A/412/657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of a CO line survey in central cluster galaxies with cooling flows are presented. Cold molecular gas is detected with the IRAM 30m telescope, through CO(1-0) and CO(2-1) emission lines in 6-10 among 32 galaxies. The corresponding gas masses are between 3x10^8^ and 4x10^10^M_{sun}. These results are in agreement with recent CO detections by Edge (2001MNRAS.328..762E). A strong correlation between the CO emission and the H{alpha} luminosity is also confirmed. Cold gas exists in the center of cooling flow clusters and these detections may be interpreted as evidence of the long searched for very cold residual of the hot cooling gas.
